1. Field of the Invention
The present invention relates to a magnetic head transferring device of a hard disk drive, and more particularly, to a magnetic head transferring device of a hard disk drive having an improved structure for locking a magnetic head in a parking zone.
2. Description of the Related Art
As shown in FIG. 1, a general hard disk drive is comprised of a hard disk 20 rotatably installed on a base 10 for storing information, and a magnetic head transferring device for moving a magnetic head 50 to a desired track position on the hard disk 20 to read and write information. Here, the surface of the hard disk 20 is divided into two sections: a recording zone 22 in which information is recorded; and a parking zone 21 provided at the inner side of the hard disk 20 where the magnetic head 50 is placed when the rotation of the hard disk 20 stops.
The magnetic head transferring device has a rotor 30 installed for pivoting around a pivot shaft 34 provided on the base 10. The magnetic head 50 is mounted on the rotor 30. The magnetic head transferring device further includes a stator 40 for actuating the rotor 30 in a pivoting motion by an electromagnetic force, and a locking means for locking the rotor 30 after the magnetic head 50 is placed in the parking zone 21. The rotor 30 is comprised of a suspension portion 31 for supporting the magnetic head 50, a swing arm 32 installed for pivoting around the pivot shaft 34 via pivot bearings 34a, and a bobbin 33 around which a coil 35 is wound for generating an electromagnetic force. The stator 40 has a magnet 41 and a yoke 42 for forming a magnetic field. Thus, as an electromagnetic force is generated due to interaction between the magnetic field generated by the magnet 41 and the yoke 42, and the current flowing through the coil 35. The rotor 30 pivots in a direction according to Fleming's left-hand rule.
The locking means is comprised of a magnetic member 43 installed on the stator 40, a damper 60 coupled to a protrusion 36 provided at an end of the bobbin 33 of the rotor 30, and a magnetic plate 61 which is bonded at an end of the damper 60. When the magnetic head 50, installed on the suspension portion 31, enters the parking zone 21 of the hard disk 20 as the rotor 30 is pivoted, the magnetic plate 61 on the bobbin 33 is attracted and stuck to the magnetic member 43, as shown in the drawing. Thus, the rotor 30 remains in a locked state in which the magnetic plate 61 and the magnetic member 43 are stuck to each other. The rotor 30 remains locked until an electromagnetic force for pivoting the rotor operates again.
However, in the conventional locking means as described above, since the rotor 30 is locked by the magnetic force generated between the magnetic plate 61 and the magnetic member 43, when an impact stronger than the magnetic force is applied in the locked state, the locked state is released. Also, in order to pivot the locked rotor 30 again, the electromagnetic force generated by the coil 35 and the magnetic member 41 must be greater than the magnetic force by which the magnetic plate 61 and the magnetic member 43 are stuck together. That is, when the magnetic force between the magnetic plate 61 and the magnetic member 43 is smaller than that between the coil 35 and the magnet 41, the locking of the rotor 30 can be easily released by a small external impact, whereas, if it is made to be stronger, the rotor 30 does not unlock well by generating an electromagnetic force.